Neil Rock checkerbloom Neil Rock checkerbloom

Plants (0.3–)0.5(–0.9) m, with caudex and taproot. Stems erect, green, often tinted pale brick-red proximally, finely stellate-pubescent (some parts ciliate, and minute simple hairs sometimes present), hairs 0.1–1 mm diam., 2(–5)-rayed. Leaves: stipules falcate, ovate-lanceolate, 5–6 × 2–2.5 mm; proximal petioles (3.5–)5–6.5(–9) cm, 1/2–3 times as long as blade, shortest (0.5–)1–2(–3.2) cm on distalmost leaves; blade usually flabelliform or reniform, often wider than long, rounded at apex, base wide-cuneate to wide-cordate, unlobed, margins coarsely crenate-

Flowering Jun (May–Jul). Rocky sandstone summits, pine-oak-Ceanothus-Cercocarpus-Toxicodendron association; of conservation concern; 800–900 m; Oreg.

Subspecies petraea is the most isolated of the subspecies and is known only from a single population on the summit of Neil Rock, Jackson County, Oregon. The white petals and predominantly two instead of three involucellar bractlets are distinctive, and its gynodioecious habit is also quite unusual for the species overall. It is likely threatened by fire suppression and possibly by recreational activity and/or mining. Subspecies petraea grows on sandstone with significant deposits of cinnabar rather than the serpentine characteristic of most of the other subspecies.